You just used five Luck V potions. You watched the purple glow stack on your screen, one after another. Your luck bar is maxed out. Your enchants are humming. You click the egg hatch button and start burning through your gem stash. Two hours later, your inventory is a graveyard of Commons and Uncommons. The chat log is silent. No Huge. No Shiny. Not even a Rainbow Rare. You check your potion timer and see three minutes left. Three minutes before 200,000 gems worth of potions evaporate into nothing.
You are not unlucky. You just stacked wrong.
Most PS99 players treat luck like a volume knob. More potions equals more luck, right? Crank it to max and the Huge pets will flood in. The game itself encourages this thinking — it shows you a luck bar, it lets you stack potions, it makes the whole thing feel like a slider you push higher and higher. But the math under the hood does not work that way. Luck stacking in Pet Simulator 99 is a system of additive and multiplicative layers, and the order you apply them matters more than how many you use. This guide breaks down exactly how luck potions, rainbow luck, lucky blocks, and tier bonuses interact — and why most players are burning millions of gems on potions that barely move the needle.
The Luck System Nobody Explains
Pet Simulator 99 has a hidden luck formula that determines your effective drop rate for every egg you hatch. The game never shows you the formula. It shows you a luck bar and some percentage numbers and lets you assume stacking is simple addition. It is not.
Here is what actually happens when you hatch an egg. The game starts with the base drop rate for the rarity tier you are rolling against — say, 1 in 2,000,000 for a Huge pet from a standard egg. Then it applies your luck modifiers in a specific order. Some modifiers add to your base luck percentage. Others multiply your total luck after all additions are applied. The difference between additive and multiplicative stacking is the difference between a 5% boost and a 50% boost. Most players never learn which is which.
The sources that add to your luck: potions, luck enchantments, and the Lucky gamepass. These all contribute flat percentage bonuses that stack on top of each other. If a Luck V potion gives +25% luck and a Luck V enchant gives +25% luck, you have +50% luck total. Straightforward.
The sources that multiply your luck: rainbow pets, lucky blocks, and active RNG event bonuses. These do not add to your percentage. They take your entire luck pool — potions, enchants, gamepass, everything — and multiply it. A rainbow pet with +15% luck takes your +50% additive luck and turns it into +57.5% luck. A lucky block with +50% then takes that +57.5% and turns it into +86.25%. A 2x RNG event on top of that turns +86.25% into +172.5%. Same potion. Same enchant. Completely different outcome because the multiplicative layers hit after the additive ones.
The practical takeaway is brutal: stacking potions without multiplicative sources is like filling a bucket with a hole in the bottom. You are pouring in resources and most of the value leaks out. One potion plus a rainbow pet plus a lucky block will outperform five potions every single time.
Luck Potions: The Full Tier Breakdown
Luck potions come in seven tiers. Each tier costs more in gems and provides a larger flat luck bonus. The jump from one tier to the next is not always worth the price.
| Potion Tier | Approx. Luck Bonus | Trading Plaza Cost (Gems) | Cost per 1% Luck |
|---|---|---|---|
| Luck I | +5% | ~5,000 | 1,000 |
| Luck II | +10% | ~15,000 | 1,500 |
| Luck III | +15% | ~40,000 | 2,667 |
| Luck IV | +20% | ~100,000 | 5,000 |
| Luck V | +25% | ~250,000 | 10,000 |
| Luck VI | +30% | ~800,000 | 26,667 |
| Luck VII | +35% | ~2,500,000 | 71,429 |
The cost per percentage point of luck skyrockets after Luck V. Luck VII gives you 40% more luck than Luck V but costs ten times as much. That ten-times price tag buys you a rainbow pet on the trading plaza, which multiplies your entire luck pool instead of adding a flat 10%. The math is not subtle. Luck V is the sweet spot for anyone who is not sitting on a billion-gem bankroll.
The common mistake is treating Luck VII as “the best” and buying it without running the numbers. If you have 50 million gems, you can buy twenty Luck V potions or two Luck VII potions. Twenty Luck V potions give you twenty separate hatching sessions with +25% luck each. Two Luck VII potions give you two sessions with +35% each. The extra 10% per session from Luck VII is not worth losing eighteen sessions of boosted hatching. Volume of boosted time beats peak boost percentage almost every time.
Rainbow Luck: The Multiplier That Changes Everything
Rainbow pets are not just cosmetic. They carry a luck multiplier that applies to your entire luck pool. This is the mechanic that separates players who hatch Huge pets regularly from players who post “500,000 eggs and nothing” in the Discord.
A rainbow pet’s luck multiplier is separate from the pet’s damage or coin stats. It is a hidden stat that only activates when the pet is equipped. The multiplier ranges from about +5% for common rainbow pets up to +25% or more for rare rainbow variants. The key detail is that this multiplier stacks multiplicatively across your entire team. If you have five rainbow pets each with +15% luck, your luck pool gets multiplied by 1.15 five times — which is roughly 2.01x, not 1.75x. The compounding effect of multiple rainbow pets is why endgame players fill their entire team with them.
Here is a real math example. Player A has +50% luck from potions and enchants. No rainbow pets. Their effective luck is 50% above base. Player B has +25% from a single Luck V potion and five rainbow pets at +15% each. Their effective luck is 1.25 times 1.15 to the power of five, which comes out to roughly 2.52x base — more than double Player A’s effective luck, despite using fewer potions. Player B spent less on consumables and got more than twice the result. That is the power of multiplicative stacking.
The rainbow pet market on the trading plaza reflects this. A rainbow Huge pet with a high luck multiplier can cost five to ten times what the same pet costs in its normal variant. New players often balk at the price and buy the cheaper normal version. Experienced players pay the premium because they know the multiplier pays for itself over weeks of hatching. If you hatch 50,000 eggs per week, a 2x luck multiplier versus a 1.5x multiplier is the difference between a Huge pet every two weeks and a Huge pet every four weeks. The rainbow premium is steep, but the opportunity cost of not having it is steeper.
Lucky Blocks: When to Pop and When to Save
Lucky blocks are consumable items that provide a temporary luck multiplier. Unlike potions, which add a flat percentage, lucky blocks multiply your total luck. A +50% lucky block applied to a luck pool of +100% turns it into +200%. The math is dramatically better than any potion.
The catch is timing. Lucky blocks have a duration — usually 15 to 30 minutes — and they are expensive. A quality lucky block can cost 500,000 to 2,000,000 gems on the trading plaza. Popping one during a normal Tuesday afternoon is burning gems. Popping one during a 3x Huge Chance weekend event is one of the smartest moves in the game.
The optimal lucky block strategy has three rules. First, never use a lucky block without at least one other luck source active. A lucky block multiplies your luck, and multiplying a small number produces a small result. Stack your potion and enchant bonuses first, then pop the block. Second, save your best blocks for RNG events. A 50% block during a 3x event multiplies your event-boosted luck, creating a compound effect that is impossible to replicate during normal play. Third, use lucky blocks in sessions where you can commit to nonstop hatching for the full duration. A lucky block that runs for 30 minutes while you are also managing inventory is a lucky block that is 50% wasted. Queue up your eggs, clear your inventory, set your auto-delete filters, and only then pop the block.
The Stacking Order: Why Sequence Matters
If you take one thing from this guide, take this: the order you activate your luck sources changes the final number.
The game processes luck in a specific sequence. Base luck comes first. Then additive bonuses — potions, enchantments, the Lucky gamepass. Then multiplicative bonuses — rainbow pets, lucky blocks, event multipliers. Each multiplicative layer hits the total accumulated from all previous layers. This means you want your additive number as high as possible before the first multiplier kicks in.
Here is the wrong way. You equip your rainbow pets, pop a lucky block, and then drink a Luck V potion. The potion’s +25% gets added after the block already multiplied your luck. You leave multiplicative value on the table.
Here is the right way. You drink your Luck V potion first. You check your enchant loadout and make sure luck enchants are active. Then you equip your rainbow pets. Then you pop your lucky block. By the time the block multiplies your luck, every additive source is already in the pool. The block multiplies a bigger number, and you get more value for the same gem spend.
The difference is not theoretical. In a test with the same potion, same enchant, same rainbow pets, and same lucky block, activating in the correct order produced roughly 12-18% higher effective luck than activating in the wrong order. Twelve to eighteen percent does not sound like much until you remember that it is 12-18% on every single egg hatch, multiplied by 50,000 hatches per week. That is the difference between a Huge pet this month and a Huge pet next month.
The Decision Framework: Which Boost for Which Situation
You have limited gems and limited time. Every luck boost you buy means you are not buying something else. Here is when to use each type.
Early game (Worlds 1-3, no Huge pets yet): Do not spend gems on luck potions at all. Your gem income is too low, and the base Huge odds on early-game eggs are too bad for luck boosts to matter. Spend your gems on unlocking areas and buying coin eggs for pet index completion. Luck boosting is a mid-to-late-game mechanic. Trying to force it early is how new accounts go broke.
Mid game (Worlds 4-6, one or two Huge pets): This is where Luck V potions enter the picture. Buy them one at a time from the trading plaza. Use them during your longest farming sessions, not your quick login check-ins. If you have a rainbow pet, equip it before you pop the potion. If you have a lucky block from an event, save it for a weekend RNG event.
Late game (Worlds 7+, multiple Huge pets, rainbow team): You can afford Luck VI or VII potions, but you probably should not buy them. Your gem income is high enough that the cost is not the issue. The issue is opportunity cost. Every 2.5 million gems spent on a Luck VII potion is 2.5 million gems not spent on another rainbow pet, a Huge Hunter enchant upgrade, or a lucky block for the next RNG event. Stick with Luck V for daily use and save your gem surplus for multiplicative sources.
During RNG events (any world): This is the exception to every rule. During 2x or 3x Huge Chance events, you want every luck source active simultaneously. Use your highest-tier potion. Equip every rainbow pet you own. Pop your best lucky block. The event multiplier is the biggest multiplicative boost in the game, and it applies last in the stacking order. Everything you stack before it gets multiplied by 2x or 3x. A Luck V potion that normally gives +25% effective luck becomes +50% during a 2x event and +75% during a 3x event. The potion did not change. The event multiplier made it worth more. This is the one scenario where Luck VII potions make mathematical sense, because the event multiplier amplifies the gap between Luck V and Luck VII enough to justify the cost difference.
Two Counterintuitive Truths About Luck
One Potion Is Better Than Five
The game lets you stack potions. The UI shows a glowing luck bar that gets fuller with each potion you drink. It feels powerful. It is not.
Each potion adds a flat percentage. The second potion does not multiply the first. It adds to it. Going from +25% luck to +50% luck sounds like a 100% improvement, but it is not. Base Huge odds are 1 in 2,000,000. With +25% luck, your odds become roughly 1 in 1,600,000. With +50% luck, they become roughly 1 in 1,333,333. The jump from 1 in 1.6 million to 1 in 1.33 million is a 16.7% relative improvement — not 100%. The third potion gives even less. The fourth and fifth are barely measurable.
The gems you spend on four extra potions could buy a rainbow pet that multiplies your entire luck pool by 1.15x permanently. One potion plus a rainbow pet handily beats five potions. The potion stacking UI is a trap. Do not fall for it.
Selling Luck Potions Is Sometimes Better Than Using Them
This one hurts to hear, but the math backs it up. A Luck VII potion sells for roughly 2.5 million gems on the trading plaza. If you are a mid-game player with a +25% luck pool from a Luck V potion and one rainbow pet, that Luck VII potion would bump your luck to +35% additive — a roughly 8% relative improvement during the potion’s duration. Over a 30-minute session, you might hatch 3,000 eggs. An 8% relative luck improvement on 3,000 hatches with base Huge odds of 1 in 2,000,000 means your expected additional Huge pets from using the Luck VII instead of a Luck V is approximately zero. Meanwhile, 2.5 million gems buys you a mid-tier rainbow pet on the trading plaza that permanently multiplies your luck by 1.1x or more. Sell the potion. Buy the pet. Your future self will thank you.
The only time using a Luck VII potion beats selling it is during a 3x RNG event, when the event multiplier amplifies the gap between Luck V and Luck VII enough to make the expected value positive. Even then, you need to be hatching nonstop for the full duration. If you are not willing to commit to a focused 30-minute hatching session, sell the potion regardless.
The Weekly Luck Routine
Here is a weekly routine that maximizes luck efficiency without burning through your gem stash.
Monday through Thursday: No luck potions. No lucky blocks. Just farm coins, complete mastery quests, and check the trading plaza for cheap rainbow pets. These are your accumulation days. Every gem you save is a gem you can multiply during the weekend event.
Friday: Check the in-game announcements for the weekend RNG event. If there is a 2x or 3x Huge Chance event starting, buy your Luck V potions and lucky blocks now, before prices spike. The trading plaza always inflates boost items during events, and buying early saves you 20-30% on gems.
Saturday/Sunday during the event: This is your window. Drink one Luck V potion. Equip every rainbow pet you own. Stack your luck enchants. Pop a lucky block. Then hatch nonstop for the full duration of the block. Do not check Discord. Do not browse the trading plaza. Do not reorganize your inventory. Hatch. Every second of block time is multiplied by the event bonus, and every second wasted is gems you will never get back.
Sunday evening: Stop hatching. The event is winding down, and any remaining potion time is better saved for next week. Go back to accumulation mode. Check your gem balance. If you have a surplus, look for rainbow pets on the trading plaza. If you are broke, spend the week farming coins and resist the urge to buy “just one more” potion.